Mechanical Characteristics of Coal Samples under Triaxial Unloading Pressure with Different Test Paths

Table 3

Values of c and φ of coal samples under different test conditions.

Lithology	Parameter	Conventional triaxial	Different rates of unloading confining pressure (MPa/s)			Ratio of unloading confining pressure parameters to conventional triaxial parameters
			0.02	0.05	0.08	0.02	0.05	0.08
Coal	C (MPa)	5.47	4.15	3.79	3.77	0.76	0.69	0.69
	φ (°)	33.31	35.63	35.50	33.56	1.07	1.07	1.01